A CHINESE ARMY WILL MARCH into London this autumn and the British Museum has planned the coup. In September, as part of a groundbreaking programme of cultural exchanges with China, it will billet a company of the terracotta warriors of Xian. This will be the largest gathering of these worldrenowned treasures to travel outside China. Our capital looks set to be taken by cultural storm.

The Emperor Qin Shihuangdi, from whose tomb the clay army was excavated, would have approved. He was a man of expansive ambitions. His name, so revered in the East, may not be as familiar in our culture, but his achievements can compare with those of Julius Caesar or Alexander the Great.

Placed on the throne of Qin in the west of China at the age of the 13, he found himself ruler of a region that was neither as wealthy nor as culturally rich as its neighbours. But it was better organised. Building on this strength, Qin managed, through sheer ambition and ruthless obsession, to subjugate and unite the warring states of China to create, within two decades, a single powerful political entity. From 221BC he ruled as the First Emperor of the vast nation to which he gave his name. (Qin is pronounced Chin).

The British Museum exhibition will tell his story — a tale of mystery, surmise and legend. The truth is elusive but the great underground necropolis that Qin constructed for himself — a sort of afterworld in which he could reign for ever — continues, like Tutankhamun’s treasures, to offer evidence of his astonishing achievements. It will be a long time before we have the opportunity to see many of the jealously-guarded treasures that will be in the show again.

The most spectacular items will be figures from the army of more than 8,000 life-sized terracotta warriors who — all facing eastwards and arranged in battle formation — have stood sentinel over Qin’s burial site for more than two millennia.

All individual, their moulded expressions distinct, their uniforms, hairstyles, weapons and armour all varied according to rank, they are not only proof of the skill of their sculptors but testimony to the martial power of the emperor. Qin unified China by force, using his army. He held his command by wiping out all opposition.

Once the nation had been unified, it was time for other developments. China, then as now, depended on administrative as much as martial strengths. Along with the terracotta army, comes a shuffle of terracotta bureaucrats: identified by the knives hanging from their belts, which would have been used to correct mistakes written on strips of bamboo. Their significance is enormous. One of the emperor’s finest achievements was to create a single written script. He travelled about his nation, inscribing mountains with records of his successes — grand proclamations about how he had pacified the four quarters — establishing a tradition of a distinctly superior form of graffiti that has continued until this day. Chairman Mao wrote his own messages on mountain sides.

Other clay figures in the show this autumn will speak of different facets of their culture. There will be acrobats, one with a plate-spinning finger, a strongman, his muscles straining as he lifts a now missing load, and musicians whose wooden instruments have long since decomposed. These last were found perched in alcoves beside a river in which great bronze cranes, geese and swans waded.

Other items excavated from Qin’s vast tomb, which covers more than 55 sq km (21 sq m), which was rediscovered by some well-digging peasants in 1974, indicate the sheer range of the First Emperor’s achievements. He was the first architect of the Great Wall (a tamped earth mound, rather than the later brick construction); he created the first road system; he unified weights and measures, coinage (a disc with a square hole in the middle) and even axlewidths, so carts could all use the same ruts.

As more sophisticated archaeological techniques have developed, more discoveries have been made. The brightly coloured lacquer that covers the terracotta figures and is destroyed on contact with the air can now be preserved so we now see that a kneeling archer has a green face. This was probably to scare evil spirits.

Arrowheads contain lead to make them poisonous. A crossbow is reconstructed complete with its trigger mechanism. And yet, for all this information about the life, culture and science of the era, many mysteries remain. The ultimate one is the principal burial mound where the emperor is entombed alongside, so story has it, his childless concubines and the 700,000 workers who built his necropolis. They were buried alive to prevent them revealing its location.

Although archaeologists are developing complex probing and scanning techniques, they are reluctant to open this mound for fear of damaging the contents.

Literary legend speaks of a miniature model of China, complete with rivers of liquid mercury flowing through it. Mercury was believed to preserve life — and may have been what killed the emperor. As he grew more powerful he consumed it in increasing quantities in the hope of living for ever. The First Emperor wanted nothing less than to rule for all eternity.

First Emperor of China will be at the British Museum from September until April 2008

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